Search Results (102)

Mannosyl erythritol lipids (MELs) are glycolipid biosurfactants produced by Ustilaginomycete yeasts. The MEL biosynthetic pathway has been characterized in Ustilago maydis where a putative transporter encoded by MMF1 is required for the secretion of the glycolipid surfactant to the extracellular space. The anamorphic yeast Moesziomyces antarcticus is a prolific producer of MELs, but the mechanism of MEL secretion is less well characterized than in U. maydis. Homologous recombination was employed to generate a disruption of the MMF1 gene in M. antarcticus JCM10317. This mutation did not prevent the intracellular accumulation of MEL species but did result in significantly reduced secretion of the conventional MEL-A, MEL-B and MEL-C species detectable by thin-layer chromatography. However, the mutant strain did secrete a glycolipid species that is distinct from conventional MEL-A/B/C and similar to a glycolipid secreted by MMF1 mutant strains of U. maydis and Pseudozyma tsukubaensis. Despite the defect in MEL secretion displayed by the M. antarcticus strain harbouring a disrupted MMF1 gene, these cells did not display a significant defect in growth or cell morphology. The findings of this investigation provide evidence that M. antarcticus MMF1 encodes a transporter required for the secretion of MELs but not required for MEL synthesis or cell growth. Full article

In the tumor microenvironment, M2 tumor-associated macrophages play a crucial role in promoting tumor growth, vascularization, and metastasis through their anti-inflammatory and tissue-repairing functions. To reprogram M2 cells into a more benign M1 phenotype and enhance the patient’s intrinsic immune response against cancer, siRNA and small molecules are used, which can be encapsulated into nanoparticles to enhance their stability, circulation time, and bioavailability. Albumin nanoparticles are ideal candidates for the delivery of such cargo because of their low toxicity, biocompatibility, biodegradability, prolonged circulation in the bloodstream, and feasible particle modification. In this study, we optimized a one-step desolvation method using the standard cross-linker glutaraldehyde and D-mannose as a second cross-linker for the synthesis of mannosylated albumin nanoparticles. The obtained nanoparticles demonstrated favorable physical characteristics, high encapsulation efficiency, and the most effective targeting into activated M2 macrophages overexpressing the mannose receptor in comparison to M1 macrophages and cancer cells in vitro. Full article

The genus Haloarcula is one of the most extensively studied genera within the class Halobacteria. In this study, analyses of average nucleotide identity (ANI), average amino acid identity (AAI), digital DNA–DNA hybridization (dDDH) values, and phylogenomic data indicated that “Haloarcula californiae” ATCC 33799 and “Haloarcula sinaiiensis” ATCC 33800 served as reference strains for Haloarcula marismortui. Furthermore, a halophilic archaeal strain, GH36^T, isolated from the inland Gahai Salt Lake in China, was subjected to comprehensive polyphasic taxonomic characterization. The ANI, AAI, and dDDH comparisons between strain GH36^T and other Haloarcula species were below the established thresholds for species demarcation. Strain GH36^T was assigned to a novel species within the genus Haloarcula based on phylogenetic, phylogenomic, and comparative genomic analyses. Moreover, distinct phenotypic differences were observed in strain GH36^T. In strain GH36^T, the primary phospholipids detected were phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), and phosphatidylglycerol sulfate (PGS), whereas the principal glycolipids were sulfated mannosyl glucosyl diether (S-DGD-1) and mannosyl glucosyl diether (DGD-1). Accordingly, the novel species Haloarcula montana sp. nov. is proposed to accommodate strain GH36^T (=CGMCC 1.62631^T = MCCC 4K00122^T). Full article

O-mannosylation is a post-translational modification required for the proper function of various proteins and critical for development and growth. POMGNT1 encodes the enzyme O-linked-mannose β-1,2-N-acetylglucosaminyltransferase 1, which catalyzes the second step in the synthesis of α-dystroglycan O-mannosyl glycans. Among POMGNT1-related α-dystroglycanopathies, muscle–eye–brain (MEB) disease presents with congenital muscular dystrophy, structural brain abnormalities, and retinal dystrophy. Defects in protein O-mannosylation due to biallelic loss-of-function POMGNT1 mutations produce disturbances in assembling and organizing the basal membrane in the neuroretinal system, involving both the central and peripheral nervous systems. In the retina, POMGNT1 is expressed in photoreceptors and is localized near the photoreceptor cilium basal body, a structure critical for protein transport. Recent studies have reported an isolated degenerative ocular phenotype without any involvement of muscular or neuronal tissues. Here, we report on a family with three siblings affected by an apparently isolated clinically variable retinal disease and sharing biallelic inactivating POMGNT1 variants. Notably, the rod-cone dystrophy phenotype in the three siblings varied significantly in onset, presentation, and severity. These findings provide further evidence of the clinical variability associated with defective POMGNT1 function. Full article

Phenylethanoid glycosides (PhGs) are widely occurring secondary metabolites of medicinal plants with interesting biological activities such as antioxidant, anti-inflammatory, neuroprotective, antiviral, hepatoprotective, immunomodulatory, etc. They are characterized by a structural core formed by a phenethyl alcohol, usually tyrosol or hydroxytyrosol, attached to β-D-glucopyranose via a glycosidic bond. This core is usually further decorated by attached phenolic acids or another saccharide. Several studies suggest an important role of the saccharidic fragment in the biological activities of PhGs, provoking demand for new glycovariants of natural PhGs. This study presents the preparation of β-mannosylated analogs of tyrosol β-D-glucopyranoside (salidroside) and hydroxytyrosol β-D-glucopyranoside (hydroxysalidroside). While the chemical synthesis of β-D-mannopyranosides is rather challenging, they can be prepared by enzymatic catalysis. We found that Novozym 188, an industrial β-glucosidase, also contains β-mannosidase and used this enzyme in the preparation of tyrosol β-D-mannopyranoside and hydroxytyrosol β-D-mannopyranoside in 12 and 16% chemical yields, respectively, by transglycosylation from β-D-mannopyranosyl-(1→4)-D-mannose. The mannosylation was chemoselective and occurred exclusively on the primary hydroxyls of tyrosol and hydroxytyrosol, and the glycosylation of phenolic moieties of the aglycons was observed. Full article

Macrophage (Mph) polarization and functional activity play an important role in the development of inflammatory lung conditions. The previously widely used bimodal classification of Mph into M1 and M2 does not adequately reflect the full range of changes in polarization and functional diversity observed in Mph in response to various stimuli and disease states. Here, we have developed a model for the direct assessment of Mph from bronchial alveolar lavage fluid (BALF) functional alterations, in terms of phagocytosis activity, depending on external stimuli, such as exposure to a range of bacteria (E. coli, B. subtilis and L. fermentum). We have employed polymeric mannosylated ligands (the “trapping ligand”) specifically targeting the CD206 receptor to selectively isolate activated Mph from the BALF of patients with pulmonary inflammatory conditions: primary ciliary dyskinesia (PCD), pneumonia and bronchial asthma. An “imaging ligand” allows for the subsequent visualization of the isolated cells using a sandwich technique. Five model strains of E. coli, MH-1, JM109, BL21, W3110 and ATCC25922, as well as B. subtilis and L. fermentum strains, each exhibiting distinct properties and expressing red fluorescent protein (RFP), were used as a phagocytosis substrate. Fluorometric, FTIR- and confocal laser scanning microscopy (CLSM) assessments of the phagocytic response of Mph to these bacterial cells were performed. Mph absorbed different strains of E. coli with different activities due to the difference in the surface villosity of bacterial cells (pili and fimbriae, as well as signal patterns). In the presence of other competitor cells (like those of Lactobacilli), the phagocytic activity of Mph is changed between two and five times and strongly dependent on the bacterial strain. The relative phagocytic activity indexes obtained for BALF-Mph in comparison with that obtained for model human CD206+ Mph in the M1 polarization state (derived from THP-1 monocyte cultures) were considered as a set of parameters to define the Mph polarization profile from the BALF of patients. Mannan as a marker determining the selectivity of the binding to the CD 206 mannose receptor of Mph significantly inhibited the phagocytosis of E. coli and B. subtilis in cases of pneumonia, suggesting an important role of CD206 overexpression in acute inflammation. Conversely, L. fermentum binding was enhanced in PCD, possibly reflecting altered macrophage responsiveness in chronic lung diseases. Our approach based on the profiling of Mph from patient BALF samples in terms of phagocytosis for a range of model bacterial strains is important for the subsequent detailed study of the factors determining dangerous conditions and resistance to existing therapeutic options. Full article

Candidemia is an opportunistic mycosis with high morbidity and mortality rates. Even though Candida albicans is the main causative agent, other Candida species, such as Candida tropicalis, are relevant etiological agents of candidiasis and candidemia. Compared with C. albicans, there is currently limited information about C. tropicalis’ biological aspects, including those related to the cell wall and the interaction with the host. Currently, it is known that its cell wall contains O-linked mannans, and the contribution of these structures to cell fitness has previously been addressed using cells subjected to chemical treatments or in mutants where O-linked mannans and other wall components are affected. Here, we generated a C. tropicalis pmt2∆ null mutant, which was affected in the first step of the O-linked mannosylation pathway. The null mutant was viable, contrasting with C. albicans where this gene is essential. The phenotypical characterization showed that O-linked mannans were required for filamentation; proper cell wall integrity and organization; biofilm formation; protein secretion; and adhesion to extracellular matrix components, in particular to fibronectin; and type I and type II collagen. When interacting with human innate immune cells, it was found that this cell wall structure is dispensable for cytokine production, but mutant cells were more phagocytosed by monocyte-derived macrophages. Furthermore, the null mutant cells showed virulence attenuation in Galleria mellonella larvae. Thus, O-linked mannans are minor components of the cell wall that are involved in different aspects of C. tropicalis’ biology. Full article

Conjugation of carbohydrates to nanomaterials has been extensively studied and recognized as an alternative in the biomedical field. Dendrimers synthesized with mannose at the end group and with entrapped zero-valent copper/silver could be a potential candidate against bacterial proliferation. This study is aimed at investigating the bactericidal activity of metal-glycodendrimers. The Cu(I)-catalyzed azide–alkyne cycloaddition (CuAAC) reaction was used to synthesize a new mannosylated dendrimer containing 12 mannopyranoside residues in the periphery. The enterotoxigenic Escherichia coli fimbriae 4 (ETEC:F4) viability, measured at 600 nm, showed the half-inhibitory concentration (IC₅₀) of metal-free glycodendrimers (D), copper-loaded glycodendrimers (D:Cu) and silver-loaded glycodendrimers (D:Ag) closed to 4.5 × 10¹, 3.5 × 10¹ and to 1.0 × 10⁻² µg/mL, respectively, and minimum inhibitory concentration (MIC) of D, D:Cu and D:Ag of 2.0, 1.5 and 1.0 × 10⁻⁴ µg/mL, respectively. The release of bacteria contents onto broth and the inhibition of ETEC:F4 biofilm formation increased with the number of metallo-glycodendrimer materials, with a special interest in silver-containing nanomaterial, which had the highest activity, suggesting that glycodendrimer-based materials interfered with bacteria-bacteria or bacteria–polystyrene interactions, with bacteria metabolism and can disrupt bacteria cell walls. Our findings identify metal–mannose-dendrimers as potent bactericidal agents and emphasize the effect of entrapped zero-valent metal against ETEC:F4. Full article

GDP-mannose transporters (GMTs) have been implicated in the virulence of some important pathogenic fungi, and guanosine diphosphate (GDP) mannose transporters transport GDP-mannose from the cytosol to the Golgi lumen prior to mannosylation, where mannose attaches to the modified protein. GMTs could be potential targets for new antifungal drugs, as disruption of any step in GDP-mannose biosynthesis can affect fungal viability, growth, or virulence. To date, the GDP-mannose transporter has been extensively studied in yeast, but its biological function in fungi, particularly F. graminearum, is still unclear. In this experimental study, the role of the GDP-mannose transporter in F. graminearum was investigated by analysing the VRG4 gene. FgGmtA and FgGmtB were blastp-derived from their Scvrg4 protein sequences and proved to be their functional homologues. The mutant and complementary strains of FgGmtA, FgGmtB and FgGmtA&B genes were generated and used to evaluate the effect of the two GMTs genes on mycelial growth, asexual reproduction, sexual reproduction, cell wall sensitivity, glyphosate synthesis and drug susceptibility. Only in the FgGmtB and FgGmtA&B mutants was the rate of mycelial growth slowed, conidium production increased, sexual reproduction impaired, cell wall sensitivity increased, glycemic content decreased, and drug sensitivity reduced. The results of the pathogenicity assessment of GMTs showed that only FgGmtB affects the patogenicity of F. graminearum. At the same time, the effect of GMTs on the ability of rhinoceros to synthesise DON toxins was investigated and the results showed that the ability of ΔFgGmtB and ΔFgGmtA&B mutants to produce the DON toxin was significantly reduced, and the expression of toxin-related genes was also reduced. Full article

The volume and stability of wine foams are influenced by many components of the matrix, especially proteins. However, the synergistic or inhibiting effects among these protein fractions, as well as their interactions with other wine components, are still under study. The present research aims to understand the individual and cooperative effects of different wine proteins and glycoproteins on the volume and stability of foams. To address this objective, different protein fractions were purified from a Chardonnay white wine and tested in different model wine conditions (with/without ethanol), along with a commercial yeast-based oenological additive. Different fractions were considered, including total protein fraction (FT), Mannoproteins (MP), and non-mannosylated proteins (NMP), as well as a protein fraction soluble in ammonium sulfate (FSA). These protein fractions were characterized, and their foaming properties were evaluated using a modified Rudin apparatus. The results showed that FT exhibited higher foam expansion (FE%) compared to its subfractions (NMP and MP) that, when tested individually, did not guarantee optimal foam formation. This suggests that foaming properties are enhanced when both glycosylated and non-glycosylated proteins are present in the system. Additionally, the foaming behavior was influenced by the presence of ethanol in the model wine. The FSA fraction demonstrated high foam expansion and stability, with ethanol enhancing foam expansion but reducing stability. A commercial yeast-based oenological additive, mainly containing glycoproteins, was also tested and behaved similarly to MP. This study provides valuable insights for sparkling wine producers to optimize practices for enhancing product quality and confirm previous research regarding the role of the synergy between MP and NMP in wine foam formation and stability. Full article

Although a lot of effort has been put into creating drugs and combination therapies against chronic hepatitis, no effective treatment has been established. Type-I interferon is a promising therapeutic for chronic hepatitis due to its excellent anti-inflammatory effects through interferon receptors on hepatic macrophages. To develop a type-I IFN equipped with the ability to target hepatic macrophages through the macrophage mannose receptor, the present study designed a mouse type-I interferon-mannosylated albumin fusion protein using site-specific mutagenesis and albumin fusion technology. This fusion protein exhibited the induction of anti-inflammatory molecules, such as IL-10, IL-1Ra, and PD-1, in RAW264.7 cells, or hepatoprotective effects on carbon tetrachloride-induced chronic hepatitis mice. As expected, such biological and hepatoprotective actions were significantly superior to those of human fusion proteins. Furthermore, the repeated administration of mouse fusion protein to carbon tetrachloride-induced chronic hepatitis mice clearly suppressed the area of liver fibrosis and hepatic hydroxyproline contents, not only with a reduction in the levels of inflammatory cytokine (TNF-α) and fibrosis-related genes (TGF-β, Fibronectin, Snail, and Collagen 1α2), but also with a shift in the hepatic macrophage phenotype from inflammatory to anti-inflammatory. Therefore, type-I interferon-mannosylated albumin fusion protein has the potential as a new therapeutic agent for chronic hepatitis. Full article

The mannose receptor (MR, CD 206) is an endocytic receptor primarily expressed by macrophages and dendritic cells, which plays a critical role in both endocytosis and antigen processing and presentation. MR carbohydrate recognition domains (CRDs) exhibit a high binding affinity for branched and linear oligosaccharides. Furthermore, multivalent mannose presentation on the various templates like peptides, proteins, polymers, micelles, and dendrimers was proven to be a valuable approach for the selective and efficient delivery of various therapeutically active agents to MR. This review provides a detailed account of the most relevant and recent aspects of the synthesis and application of mannosylated bioactive formulations for MR-mediated delivery in treatments of cancer and other infectious diseases. It further highlights recent findings related to the necessary structural features of the mannose-containing ligands for successful binding to the MR. Full article

Protein glycosylation is an essential post-translational modification in all domains of life. Its impairment in humans can result in severe diseases named congenital disorders of glycosylation (CDGs). Most of the glycosyltransferases (GTs) responsible for proper glycosylation are polytopic membrane proteins that represent challenging targets in proteomics. We established a multiple reaction monitoring (MRM) assay to comprehensively quantify GTs involved in the processes of N-glycosylation and O- and C-mannosylation in the endoplasmic reticulum. High robustness was achieved by using an enriched membrane protein fraction of isotopically labeled HEK 293T cells as an internal protein standard. The analysis of primary skin fibroblasts from eight CDG type I patients with impaired ALG1, ALG2, and ALG11 genes, respectively, revealed a substantial reduction in the corresponding protein levels. The abundance of the other GTs, however, remained unchanged at the transcript and protein levels, indicating that there is no fail-safe mechanism for the early steps of glycosylation in the endoplasmic reticulum. The established MRM assay was shared with the scientific community via the commonly used open source Skyline software environment, including Skyline Batch for automated data analysis. We demonstrate that another research group could easily reproduce all analysis steps, even while using different LC-MS hardware. Full article

Semen prostatic acid phosphatase (PAP) has been proposed as an endogenous ligand for dendritic cell-specific ICAM-3-grabbing nonintegrin (DC-SIGN), which plays a critical immuno-modulating role in maintaining homeostasis in the female reproductive tracts. In the current study, we assumed that semen PAP bears a set of fucosylated and mannosylated glycans, which may mediate the efficient binding of PAP to DC-SIGN. To investigate this hypothesis, we developed ELISA assays using Galanthus nivalis and Lotus tetragonolobus lectins capable of binding mannose-containing glycans or LewisX and LewisY motifs, respectively. In our assay with Galanthus nivalis, we detected that the relative reactivity of PAP mannose-presenting glycans in the normozoospermic idiopathic group was significantly higher than in the asthenozoospermic, oligozoospermic and oligoasthenozoospermic groups. Simultaneously, we observed slight differences in the relative reactivities of PAP glycans with Lotus tetragonolobus lectin among groups of patients with abnormal semen parameters. Subsequently, we examined whether DC-SIGN interacts with seminal plasma PAP glycans, and we detected a significantly higher relative reactivity in the normozoospermic group compared to the oligozoospermic group. Finally, we concluded that the significantly aberrant abundance of mannosylated functional groups of PAP among patients with semen disorders can suggest that PAP may thereby be engaged in modulating the immune response and promoting a tolerogenic response to male antigens in the female reproductive system. Full article

Metformin is the first-line oral medication for treating type 2 diabetes mellitus (T2DM). In the current study, an untargeted lipidomic analytical approach was used to investigate the alterations in the serum lipidome of a cohort of 89 participants, including healthy lean controls and obese diabetic patients, and to examine the alterations associated with metformin administration. A total of 115 lipid molecules were significantly dysregulated (64 up-regulated and 51 down-regulated) in the obese compared to lean controls. However, the levels of 224 lipid molecules were significantly dysregulated (125 up-regulated and 99 down-regulated) in obese diabetic patients compared to the obese group. Metformin administration in obese diabetic patients was associated with significant dysregulation of 54 lipid molecule levels (20 up-regulated and 34 down-regulated). Levels of six molecules belonging to five lipid subclasses were simultaneously dysregulated by the effects of obesity, T2DM, and metformin. These include two putatively annotated triacylglycerols (TGs), one plasmenyl phosphatidylcholine (PC), one phosphatidylglycerol (PGs), one sterol lipid (ST), and one Mannosyl-phosphoinositol ceramide (MIPC). This study provides new insights into our understanding of the lipidomics alterations associated with obesity, T2DM, and metformin and offers a new platform for potential biomarkers for the progression of diabetes and treatment response in obese patients. Full article